Issue description: Turning on or off the support blocks in the builder causes a ticking world crash

Steps to reproduce: Place a shape card, click one of the directional corners or enter the dimensions in by hand. enter support preview.

Versions:

• Minecraft: 1.12.2
• Forge: 1.12.2-14.23.5.2838
• CompatLayer (only if on Minecraft 1.10 or 1.11): N/A
• McJtyLib: 1.12-3.5.3
• RFTools: 1.12-7.71

All that is installed is Minecraft, Forge, JEI, RFTools, Xnet, and mcjtylib,
crash-2019-06-20_02.19.01-server.txt

crash-2019-06-20_02.19.01-server.txt

(I hope I didn't attach it twice. If so, it's small.

I have the same problem. Also the preview blocks are persisting after turning off the preview.

Really? The rftools builder isn't yours?

It is. But where is the rftools builder mentioned in that crashlog?

well, I'm not exactly sure what you mean, but on line
159: mcjtylib_ng | 3.5.3 | mcjtylib-1.12-3.5.3.jar
165; rftools | 7.71 | rftools-1.12-7.71.jar
Not to mention it happens almost immediately after I toggle Support/preview mode
and I tried it twice to make sure.

Same, but I think I have a better crash log if you need it.
Minecraft 1.12.2
Forge 14.23.5.2838
rftools 1.12-7.71

Mod List: https://pastebin.com/RT9gtjNJ
Crash log: https://pastebin.com/wSrHqPf6
edit: I'm using the quarry shape card when it occurs.

Problem is that neither of these crashlogs including anything of my mods so I have no clue what's going on here

After testing (by the reporting user at the Enigmatica 2 pack) with an instance using just RFTools, and McJtyLib it is reproducible. Rendering the first preview goes fine; the second one crashes the game.

Corresponding logs: here

Mods present:

• forge 14.23.5.2836
• mcjtylib 3.5.3
• rftools 7.71

Additional information provided by the user:

extremely small previews don't crash
50x20x50 box worked without problems
but a 90x20x90 caused an immediate crash

Steps to reproduce:

1. Place down an RFTools Builder.
2. Insert a Shape card with (at least?) a 90x20x90 solid box inside.
3. Render a support block preview of the structure.

We just had a user of the Enigmatica 2 pack report this same issue in Discord. I asked them to post their logs in here as well. Same thing though, no reference to RFTools specifically; but it is a reproducable crash using rftools-1.12-7.71.

EDIT: they don't have a GitHub account, so let me post it for them https://puu.sh/DUqAx/4a116d6782.txt

EDIT2: I asked them to try and reproduce the issue on a server running just RFTools and let us know the results and provide a crash log.

Ok. I was finally able to reproduce it. Now I have to figure out what causes it

If there's anything we can do on our end in terms of testing, please let me know.

Found and fixed for next release (very soon)